Yeah, I remember the bot used to do some really dumb things like a) dogpile on mechwarriors and b) cluster around disabled vehicles without firing on them. There was also a pretty subtle bug which probably resulted in a lot of dumb behavior, although that's hard to quantify - one of the things the bot does is it gives each unit a "potential movement range" hex, which it uses to determine roughly where a given unit can go. There was an arithmetic error that caused the left half of that hex to get chopped off, so basically, if you were to the right of a bot's units it would underestimate your movement range and do dumb things.
I got rid of most of the low-hanging fruit for really dumb bot behavior a while back, there's one remaining behavior which annoys me to no end - if a bot unit has a "destination edge" or is attempting to move to engage hostile units and is out of range, it may get stuck in a cul-de-sac and then spend the rest of the battle humping a wall. You can get them un-stuck by destroying the obstacle or moving a unit so that they have incentive to come out of said cul-de-sac, but I'd really rather have the bot solve that problem on its own. Of course, the solution requires quite a bit of work, so it's not exactly a low-hanging fruit.
With respect to mechwarriors, as far as the fiction goes (especially during the FedCom civil war), there was a lot of targeting of mechwarriors, so it's not entirely unprecedented. But still pretty inefficient to waste a whole turn emptying out an alpha strike into a single dude. Game-wise, one of the reasons I have mechwarriors on is so that, when my deployed forces start getting beat up, there's at least an extra initiative sink on the board to make up for the combat loss a little.
All Weather is ok, but I wouldn't pay XP for it. I guess Ragu's massacre of a couple of infantry squads (pretty sure the Packrat only carries the two squads) was pretty impressive, huh?